System and methods for detecting, monitoring, and removing deposits on boiler heat exchanger surfaces using dynamic pressure analysis

ABSTRACT

A boiler system includes a boiler having at least one internal surface on which a deposit may form. The boiler system further includes at least one cleaning implement coupled to a high-pressure fluid supply for carrying a high-pressure fluid into the boiler. The cleaning implement is configured such that the high-pressure fluid impacts the surface. The boiler system also includes at least one pressure measuring device coupled to the high-pressure fluid system. The pressure measuring device is configured to measure at least one of the pressure or flow rate in a high-pressure fluid supply, and the measured pressure and/or flow rate indicates presence or absence of the deposit on the surface.

FIELD

The present invention relates generally to fouling or ash deposits inboilers and, more particularly, to a system and methods for detecting,monitoring, measuring, and/or removing the deposits on heat exchangersof the boilers by using dynamic pressure monitoring and analysis.

BACKGROUND

Many energy sources burned in boilers to generate steam will produce ashproducts with the potential for fouling the internal components of theboiler, which can decrease the operating efficiency of the boiler. Forexample, in the paper-making process, chemical pulping yields blackliquor as a by-product. Black liquor contains inorganic cookingchemicals along with lignin and other organic matter that separates fromwood during pulping in a digester. The black liquor is burned in aboiler. The two main functions of the boiler are to recover theinorganic cooking chemicals used in the pulping process and to make useof chemical energy in the organic portion of the black liquor togenerate steam for a paper mill. Other examples include boilers thatburn coal and biomass to generate steam for energy production or otheruses. As used herein, the term boiler includes any boiler that burns afuel that, in the process, fouls internal structures of the boiler,including heat transfer surfaces.

An example of a boiler used to burn black liquor to generate steam is aKraft boiler. A Kraft boiler includes banks of heat exchangers atvarious levels in the furnace for extracting heat by radiation andconvection from the furnace gases to generate heated fluids such assteam. Typically, the furnace gases first interact with heat exchangersin a superheater bank to generate superheated steam. The furnace gasesthen interact with heat exchangers in a generating bank to generateworking steam. The generating bank may also be referred to as a boilerbank. Finally, the furnace gases interact with heat exchangers in aneconomizer bank, which generates lower temperature heated fluids. Thebanks of heat exchangers are constructed of an array of platens that areconstructed of tubes that function as heat exchanger surfaces forconducting and transferring heat. While operating, heat exchangersurfaces are continually fouled by ash generated in the furnace chamberfrom burning fuels such as black liquor or coal. The amount of fuel thatcan be burned in a boiler is often limited by the rate and extent offouling on the surfaces of the heat exchangers. The fouling, includingash deposited on the heat exchanger surfaces, reduces the heat absorbedfrom fuel combustion, resulting in reduced exit steam temperatures inthe fouled heat exchanger banks and high gas temperatures entering thenext heat exchanger bank in the boiler. For example, fouling in thesuperheater bank results in decreased steam temperatures exiting theheat exchanger and increased furnace gas temperature entering thegenerating bank. The heat exchanger surfaces in the generating bank tendto be relatively narrow compared to the spacing in the superheater andeconomizer banks, which increases the likelihood of fouling in thegenerating bank as compared to fouling in the superheater and economizerbanks.

Fouling can require a boiler to be shut down for cleaning when eitherthe exit steam temperature is too low for use in downstream equipment orthe temperature entering the downstream heat exchanger bank, such as thegenerating bank downstream from the superheater bank, exceeds themelting temperature of the deposits, resulting in gas side pluggage ofthe downstream bank. In addition, fouling can eventually cause pluggingin the upstream bank as well, such as the superheater bank. In order toremove the plugging from the heat exchanger banks, the burning processin the boiler must be stopped. Kraft boilers are particularly prone tothe problem of fouling in the generating bank with ash deposits thatmust be removed for efficient operation; however, the other heatexchanger banks may also become fouled. Three conventional methods ofremoving ash deposits from the heat exchanger banks in boilers: 1)sootblowing, 2) chill-and-blow, and 3) water washing. Sootblowing is aprocess that includes blowing deposited ashes off a heat exchangersurface that is fouled with ash deposits using blasts of high-pressuresteam from nozzles of a lance of a sootblower. Sootblowing is performedessentially continuously during normal boiler operation, withsootblowers in various locations in operation at different times.Sootblowing is usually carried out using high-pressure steam, but otherfluids may be used. The steam consumption of an individual sootblower istypically 2-3 kg/s, and as many as four sootblowers may be operatedsimultaneously. Typical sootblower usage may consume about 3-7% of thesteam production of the entire boiler. Thus, the sootblowing procedureconsumes a large amount of thermal energy produced by the boilers beingcleaned.

A typical sootblowing process utilizes a procedure known as sequencesootblowing, wherein sootblowers operate at predetermined intervals andin a predetermined order. The sootblowing procedure runs at this paceirrespective of the amount of fouling that may occur at any particularlocation in the heat exchanger. Often, this leads to plugging in areasof the heat exchanger that are insufficiently cleaned by thepredetermined sootblowing sequence that cannot necessarily be preventedeven if the sootblowing procedure consumes a large amount of steam. Eachsootblowing operation reduces a portion of nearby ash deposits, but ashdeposits that are not completely removed may nevertheless continue tobuild up over time. As ash deposits grow, sootblowing becomes graduallyless effective and impairs heat transfer. When an ash deposit reaches acertain threshold where boiler efficiency is significantly reduced orcombustion gases cannot be removed from the furnace, deposits may needto be removed by another cleaning process requiring the boiler to beshut down. However, overusing the sootblowing procedure across theentire boiler can also decrease the operating efficiency of the boilerby consuming the thermal energy produced by the boiler and can damagethe boiler tubes by causing erosion and corrosion of the tube surface.

SUMMARY

It is desirable to monitor the pressure in the supply of high-pressurefluid of a boiler cleaning implement, such as a sootblower or watercannon. The dynamic response of the pressure in the supply ofhigh-pressure fluid can be monitored for signals that define the profileof a fouled surface along the path of the cleaning implement. In anembodiment, the signal is a change in the pressure of the supply ofhigh-pressure fluid that results from the high-pressure fluid expelledfrom the cleaning implement contacting fouling, such as a deposit, on asurface in the boiler system. The dynamic pressure signal in the supplyof high-pressure fluid is then used to detect, monitor, measure, and/orremove ash deposits from the surfaces of boilers, such as heat exchangersurfaces, and, as a result, conserve energy by directing sootbloweractivity to areas in need of cleaning and thus having the cleaningimplement use a minimum amount of high-pressure fluid such as steam,air, or water.

It is also desirable to develop a map of the deposition pattern ofdeposits surrounding the path of each of the cleaning implements so thatthe information in the map may be used to adjust priority of cleaningimplement operations for efficient use and, in general, to develop aneffective cleaning strategy.

It is also desirable to monitor the operating condition of the boilercleaning implements such as by monitoring the pressure in the supply ofhigh-pressure of the boiler cleaning implement or vibrations in orcoming from the boiler cleaning implement. The operating conditions mayinclude poppet valve condition, bearing condition, and leaks in thesupply of high-pressure fluid.

An aspect of the invention is directed to a boiler system that includesa boiler having at least one heat exchanger, the at least one heatexchanger having a surface on which a deposit may form. The boilersystem further includes at least one cleaning implement which may beselected from a sootblower having a lance tube or water canon forcarrying a high-pressure fluid into the boiler. The cleaning implementis configured such that the high-pressure fluid impacts a surface in theboiler. The boiler system also includes at least one pressure measuringdevice coupled to the supply of high-pressure fluid to the cleaningimplements of the boiler system, the pressure measuring device beingconfigured to measure changes in pressure in the supply of high-pressurefluid that results from high-pressure fluid contacting the boilersurfaces or deposits on the boiler surfaces. The measured pressurechanges of the high-pressure fluid supply to the cleaning implementindicates presence or absence of the deposit on a boiler surface, suchas a heat exchange surface. Another aspect of the invention may includevibration measuring devices used either in concert with the pressuremeasuring device or independent of the pressure measuring device. Thevibration measuring device may be used to identify the presence ofdeposits in the boiler system as well as the operating condition of theboiler cleaning implement or the supply of high-pressure fluid.

Another aspect of the invention is directed to a method of detecting adeposit on at least one surface of a boiler that includes moving acleaning implement relative to the at least one boiler surface andimpacting the at least one boiler surface with high-pressure fluiddischarged from the cleaning implement. The method further includesmeasuring a pressure change in the supply of high-pressure fluid to thecleaning implement caused by the impact of the high-pressure fluid withthe at least one boiler surface and analyzing the measured pressure todetect the presence of the deposit at the location.

Another aspect of the invention is directed to methods of mapping thelocation deposits in a boiler system. The method includes identifyingthe location of a deposit on a boiler surface based on reactive pressurechanges in the supply of high-pressure fluid generated by impactingdeposits with the high-pressure fluid discharged from a cleaningimplement. A deposit map may then be generated based on the positions ofthe identified deposits.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated in and constitute apart of this specification, illustrate various embodiments of theinvention and, together with a general description of the inventiongiven above and the detailed description of the embodiments given below,serve to explain the embodiments of the invention.

FIG. 1 is a schematic illustration of a boiler system in accordance withan embodiment of the invention;

FIG. 2 is an enlarged detail of top perspective view of a portion of theboiler system shown in FIG. 1 illustrating a number of accelerometerspositioned on hanger rods supporting a number of platens; and

FIG. 3 is a flow chart illustrating a process for analyzing signals froma pressure measuring device to identify the presence of deposits inaccordance with an embodiment of the invention.

DETAILED DESCRIPTION

FIG. 1 is a schematic illustration of a boiler system 10 having a boiler12 including a plurality of heat exchangers 22 with deposits 20 formedthereupon, pressure measuring device 14, a cleaning implement, in thisillustrated embodiment a sootblower 16, a deposit detection device 18,and an integrated device 30.

For the purposes of the present invention, the term “boiler” 12 refersto a closed vessel in which water or other fluid is heated in heatexchangers that are contacted by hot gases from a combusted fuel.Exemplary boilers 12 include a recovery boiler and a utility boiler. Theheated or vaporized fluid exits the boiler 12 for use in variousprocesses or heating applications, including boiler-based powergeneration, process heating, and the like.

The term “recovery boiler” includes the type of boiler 12 that is partof the Kraft process of pulping where chemicals for pulping arerecovered and reformed from black liquor, which contains lignin (amongother organic materials) from previously processed wood. The blackliquor is burned, generating heat, which is usually used in the processor in making electricity, much as in a conventional steam power plant.The two main functions of recovery boilers are to recover the inorganiccooking chemicals used in the pulping process and to use the chemicalenergy in the organic portion of the black liquor to generate steam forthe mill. A detailed description of Kraft black liquor boilers aredescribed in detail in U.S. Pat. Nos. 6,323,442 and 7,341,067, which areincorporated by reference herein in their entireties.

With reference to FIGS. 2 and 3, the boiler 12 comprises a series ofheat exchangers 22. The heat exchangers 22 may be organized into asuperheater bank, a generating bank, an economizer bank, andcombinations thereof. The heat exchangers 22 are formed of tubes(FIG. 1) or platens (FIG. 2) having surfaces 48. Each heat exchanger 22may comprise approximately 20-100 tubes, for example. The heat exchangersurfaces 48 have passages 50 upstream and/or downstream therethrough toallow a sootblower 16 to move relative to the heat exchanger surfaces48, as will be described in greater detail below.

In an embodiment, the boiler 12 is suspended from a ceiling with boilersupporting structures that may include overhead beams 34 and hanger rods32. The overhead beams 34 may include I-beams. Approximately 30-100hanger rods 32 (FIG. 2) may be used to suspend the boiler 12 from theoverhead beams 34. More specifically, the hanger rods 32 may be boltedor otherwise coupled to the overhead beams 34 at one end and coupled tothe heat exchangers 22 either directly or via headers 36 (FIG. 2) at anopposite end. The hanger rods 32 typically have a diameter that rangesfrom about 1 inch to about 3 inches and length range from about 2 feetto about 20 feet long.

As explained above during use, slag and/or ash deposits 20 may form onthe surfaces 48 of the boiler 12 including the heat exchangers 22, theinternal surfaces 37 of the walls of the boiler 12, which degradesthermal performance of the boiler system 10. The amount of the deposit20 may vary at different locations in the boiler 12 on the heatexchanger surfaces 48 and the internal surfaces 37 of the walls.

The boiler system 10 includes one or more sootblowers 16 for cleaningdeposits 20 from the heat exchanger surfaces 48. For example, a boilersystem 10 may include a plurality of sootblowers 16 spaced apart byapproximately 5-15 feet within the boiler 12. For the purposes of thepresent invention, the term “sootblower” 16 refers to an apparatus usedto project a stream of a high-pressure fluid 24, such as steam, air,water or other fluid against heat exchanger surfaces 48 of large-scalecombustion devices, such as utility or recovery boilers. Generally, thesootblowers 16 include a lance tube 26 that is in fluid communicationwith a source (not shown) of high-pressure fluid 24, such as steam. Asillustrated in FIG. 2, each sootblower 16 may also include a motor 76for rotating the lance tube 26. The motor 76 is typically suspended froma rail 78 by one or more rollers 80 that couple the motor to a hood 82.The rail 78 allows the motor 76 to move with the lance tube 26 as thelance tube 26 translates in and out of the boiler 12, as described ingreater detail below. The hood 82 covers the motor 76 and rail 78 andtypically provides at least one attachment point, such as a pair ofbrackets 84, for coupling the sootblower 16 to an external supportstructure 88. For drafting efficiency, only a subset of the sootblowers16 illustrated on FIG. 2 are shown as including motors 76, rails 78, andhoods 82. However, it is appreciated that in embodiments of theinvention, all of the sootblowers 16 in a boiler system 10 include theseadditional structures.

While the exemplary embodiment illustrated herein utilize sootblowers 16expelling steam, it is noted that embodiments of the invention are notso limited, and the sootblowers 16 may also use other high-pressurefluids 24, such as air, water, or other fluids, and other cleaningimplements such as water cannons. In embodiments of the invention, thehigh-pressure fluid 24 may be supplied via a supply line at a pressureof approximately 100-400 psi. Each sootblower 16 also includes at leastone nozzle 28 at the distal end 29 of the lance tube 26 of thesootblower 16. In an embodiment, each sootblower 16 includes two nozzles28 that are spaced 180° apart at the distal end 29 of the lance tube 26.

As described in greater detail below, a retractable sootblower 16 isconfigured such that the lance tube 26 translates (i.e., periodicallyadvance and retract) in and out of an interior of the boiler 12 as thehigh-pressure fluid 24 is discharged from the nozzles 28. The lance tube26 of the sootblower 16 may also be configured to rotate while thehigh-pressure fluid 24 is discharged from the nozzles 28.

The boiler system 10 also includes one or more pressure measuringdevices 14 coupled to the boiler system 10 to measure pressure in thehigh-pressure fluid supply of the cleaning implements, e.g. sootblowers16 or water cannons, in the boiler system 10. Exemplary pressuremeasuring devices 14 may include a pressure transducer, a fluid velocitymeasurement device, and combinations thereof. In an embodiment, thepressure measuring device is a pressure transducer. The pressuremeasuring devices 14 are mounted on strategic locations along the flowpath of high-pressure fluid supply in the boiler system 10. In anembodiment, the pressure measuring device is mounted along the pressureline between the cleaning implement and the source of this high-pressurefluid. For example, the pressure measuring device may be mounted alongthe pressure line leading to an individual cleaning implement. In anembodiment of this exemplary structure, the pressure measuring device isin the supply line as close to the individual cleaning implement aspossible. An advantage of this location for the pressure measuringdevice is isolating the pressure measuring device from interference ornoise from other sources or sinks in the high-pressure fluid supply. Inanother example. The pressure measuring device may be located upstreamalong the pressure line serving multiple cleaning implements. Thisexemplary structure would allow a single pressure measuring device tomonitor multiple cleaning implements. In another embodiment, thepressure measuring device is located along or on the sootblower 16, suchas in the lance tube 26. The pressure measuring devices 14 collectpressure data, such as changes in amplitude and natural frequency, inthe supply of high-pressure fluid to the cleaning implements of theboiler system 10 that occurs as a result of the high-pressure fluidexpelled from the cleaning implement contacting a deposit on a boiler 12surface such as on boiler surfaces of the boiler walls. The pressuremeasuring device 14 could also monitor the operating conditions of thecleaning implements, the high-pressure supply, and combinations thereof.The operating conditions that may be monitored include the condition ofpoppet valves in the high-pressure fluid supply, the condition ofmechanical aspects of the cleaning implement such as bearings or gears,and the occurrence of leaks or reductions in flow rate or pressure inthe high-pressure fluid supply lines.

In an embodiment, the system may also include vibration detectingdevices 90 to detect vibrations in or coming from the boiler cleaningimplement or the high-pressure fluid supply. The vibration detectingdevices 90 may be used in concert with the pressure measuring device 18or independently. The vibrations detected by the vibration detectiondevices could be used to monitor the operating condition of the boilercleaning implement or the high-pressure fluid supply. Exemplaryvibration detecting devices 90 include accelerometers. The vibrationdetecting devices may directly detect vibrations in the boiler system orbe coupled to a diaphragm to detect vibrations in a medium such as air,which may be manifest as oscillating wave of pressure and displacementin the medium, that originated in the boiler system. In an embodiment,the vibration detecting device 90 is coupled directly to the boilersystem via at least one of the boiler, boiler support structures, thecleaning implement, the support structures of the cleaning implement, orthe high-pressure fluid supply. In another exemplary embodiment, thevibration measuring device is spaced apart from the boiler system tomeasure vibrations in the air.

The system also includes a deposit detection device 18 that receivesinput for the pressure measuring devices 14 as well as the optionalvibration measuring device 90 and optionally communicates with theintegrated device 30 that may control the operation of the cleaningimplement such as a sootblower 16. The deposit detection device 18includes software configured to interpret pressure data received fromthe pressure measuring devices 14 and to provide instructions to theintegrated device 30, so as to direct operation of the cleaningimplement sootblower 16 and the lance tube 26.

The sootblowers 16 are periodically operated to clean the heat exchangersurfaces 48 to restore desired operational characteristics. In use, alance tube 26 of a sootblower 16 moves relative to heat exchangersurfaces 48 through passages 50. The sootblowers 16 are inserted intoand extracted from the boiler 12 such that the nozzles 28 move between afirst position located outside of the boiler 12 and a second positionlocated inside the boiler 12. As the nozzle 28 on the lance tube 26 ofthe sootblower 16 move between the first and second positions, thenozzle 28 rotates adjacent the heat exchanger surfaces 48 such that thehigh-pressure fluid 24 is expelled about a radius along the path of thenozzle 28 between the first and second positions. In an embodiment, thesecond position is the maximum inserted position. The sootblowers 16move generally perpendicularly to the heat exchanger surfaces 48 as thelance tubes 26 move through the passages 50.

The movement of the sootblower 16 into the boiler 12, which is typicallythe movement between the first and second positions, may be identifiedas a “first stroke” or insertion, and the movement out of the boiler 12,which is typically the movement between the second position and thefirst position, may be identified as the “second stroke” or extraction.Generally, sootblowing methods use the full motion of the sootblower 16between the first position and the second position; however, a partialmotion may also be considered a first or second stroke. Thehigh-pressure fluid is usually applied during both the first and secondstrokes.

As the sootblower 16 moves adjacent to the heat transfer surfaces 48,the high-pressure fluid 24 is expelled through the openings in thenozzle 28. The impact of the high-pressure fluid 24 with the deposits 20accumulated on the heat exchanger surfaces 48 produces both a thermaland mechanical shock that dislodges at least a portion of the deposits20. However, some amount of deposit 20 remains. As used herein, the term“removed deposit” refers to the mass of a deposit that is removed by thesootblowing procedure, and “residual deposit” refers to the mass of adeposit that remains on a heat exchanger surface 48 after a sootblowingcycle.

The impact of the high-pressure fluid 24 on the heat exchanger surfaces48 affects the flow of high-pressure fluid in the high-pressure fluidsupply line and can cause changes in the pressure or flow rate, or boththe pressure and flow rate, which may be detected and measured by one ormore of the pressure measuring devices 14. The impact of thehigh-pressure fluid 24 on the heat exchanger surfaces 48 may also affectthe pressure of the high-pressure fluid in the high-pressure fluidsupply line and can cause changes in the pressure or flow rate, or boththe pressure and flow rate, of the high-pressure fluid supply, which maybe detected and measured by one or more of the pressure measuringdevices 14. The changes in the pressure or flow rate, or both thepressure and flow rate can be caused directly by the impact of thehigh-pressure fluid 24 with the heat exchanger surfaces 48 orindirectly, such as by reflection of the fluid off the heat exchangersurfaces 48 back into the flow path of the high-pressure fluid 24.

As an amount of deposit 20 buildup changes on the heat exchangersurfaces 48, the effect of the deposit 20 on the pressure and/or flowrate of high-pressure fluid in the high-pressure fluid changes. As thesize of a deposit 20 increases, the pressure in the high-pressure fluidsupply will increase or the flow rate may decrease. As the size of thepressure applied by the high-pressure fluid 24 delivered by the deposit20 decreases, the pressure in the high-pressure fluid supply willdecrease or the flow rate may increase. The pressure, or flow rate, orboth the pressure and flow rate of the high-pressure fluid supply to acleaning implement, such as a sootblower 16 or water cannon can beanalyzed to detect the presence of residual deposits. The amount ofpressure in the high-pressure fluid supply that results from thehigh-pressure fluid 24 contacting a deposit is a direct function of ordirectly proportional to the amount of deposit 20 buildup on a heatexchanger surface 48. In other words, increased pressure in thehigh-pressure fluid, as indicated by increase in the pressure ordecrease in flow rate measured in the high-pressure fluid supply,signifies an increase in deposit 20 buildup on the boiler surface beingcleaned, such as on the heat exchanger surface 48 internal wall of theboiler.

The pressure in the high-pressure fluid supply is proportional to thesurface area perpendicular to the high-pressure fluid flow hitting adeposit 20 on the boiler surfaces. The surface area of the deposit 20may correlate to the mass of the deposit 20. The changes in pressure orflow rate in the high-pressure fluid supply that result from thepressure buildup caused by the high-pressure fluid impacting deposits 20on the boiler surface can be used to determine an amount ofhigh-pressure fluid 24 the sootblower 16 needs to deliver to remove thedeposits 20 from the boiler surface such as a heat exchanger surface 48.Aspects of the present invention are directed to analyzing the changesin pressure, flow rate, or both, in the high-pressure fluid supplyproduced by the forces transmitted to the high-pressure fluid supply bythe high-pressure fluid 24 expelled from the cleaning implementcontacting deposits 20 on the boiler surfaces. Therefore, the concept ofenergy excitation response is used to determine the location and removalof the deposits 20. The measured pressure and/or flow rate in thehigh-pressure fluid supply may then be used to control a flowcharacteristic of the high-pressure fluid 24, such as an amount ofhigh-pressure fluid 24 discharged from the nozzle 28 on the lance tube26 or a flow rate of the high-pressure fluid 24 to more efficientlyclean the boiler surfaces.

An aspect of the invention is directed to methods of mapping deposits 20on one or more heat exchanger surfaces 48 in a boiler system 10. Adeposit map is generally a spatial representation of the location ofeach sootblower 16 in the boiler 12 and the respective deposit 20buildup profiles as determined by the path of the individual sootblower16 within the boiler 12. A deposit map may be generated by moving atleast one lance tube relative to at least one heat exchanger surfacewhile discharging a high-pressure fluid 24. The high-pressure fluid 24impacts deposits on the heat exchanger surfaces resulting in pressureand/or flow rate changes in the high-pressure fluid supply that may bemeasured to identify the presence of a deposit. Thus, by incrementallyand simultaneously translating and rotating the nozzle 28 on the lancetube 26 at a set penetration distance into the boiler 12, deposits 20may be detected at a plurality of locations on the heat exchangersurfaces 48. The position of the nozzle 28 on the lance tube 26 of thesootblower 16 relative to the heat exchanger surfaces 48 when a depositis identified may then be used to determine the position of identifieddeposits 20 along the path of the nozzle 28 on the lance tube 26 of thesootblower 16. The position of deposits 20 identified along the path ofnozzle 28 of each sootblower 16 may be used to generate a map ofdeposits 20 at each sootblower 16 location.

In an embodiment, the map may be represented as a table that identifiesthe sootblower 16 and the position along the path of the identifiedsootblower 16 where a deposit 20 is detected. The table may alsoidentify the relative location of the sootblower 16 in the boiler system10. In another embodiment, the map is a two-dimensional representationof one or more deposits 20 on the heat exchanger surfaces 48 along thepath of a sootblower 16. In another embodiment, the map is athree-dimensional representation of one or more deposits 20 on heatexchanger surfaces 48 along the paths of a plurality of sootblowers.Because a conventional boiler may have, depending on the size, from justa few to more than one hundred sootblowers 16 located across the heightand width of the boiler 12, detailed maps of deposits 20 may beobtained. Successive deposit maps may change as the heat exchangersurfaces 48 become fouled or are cleaned and relative changes in deposit20 build up or position may be illustrated on the successive maps.

The generated maps may assist with identifying areas in the boilersystem 10 in which deposits 20 do not form, areas where the sootblowers16 are adequately removing deposits, and areas where residual depositsremain and that may require additional sootblower 16 activities toremove. These data may be used to develop an efficient sootblowingstrategy that reduces steam consumption for energy savings or improvesheat exchanger surface 48 effectiveness. For example, a sootblower 16could be operated in “deposit 20 location mode” periodically, forexample, once per day, and the collected information may be used toupdate a current deposit map. This map may be used to adjust thepriority of sootblower 16 operations for effective and efficient use ofthe sootblower 16 and to reduce steam consumption for energy savings.

Referring now to FIG. 3, a flow chart depicting a process 100 foranalyzing a signal from a pressure measuring device 14 is presented inaccordance with an embodiment of the invention. The analytical process100 includes a sequence of operations that may be performed by thedeposit detection device 18.

In block 102, a threshold for determining the presence of an eventindicative of a residual deposit on a boiler surface, such as a heatexchanger surface 48 or internal boiler wall is established. Thethreshold is a value or a range of values against which the signal fromthe pressure measuring device 14 may be compared. In embodiments of theinvention, a narrow frequency range of the signal from the pressuremeasuring device 14 is analyzed for the presence of an event. Forexample, the threshold may be a pressure or a flow rate. In an exemplaryembodiment, the threshold is predetermined and can be based onhistorical data. The historical data can include data taken when theboiler is clean such as just after startup. In an alternativeembodiment, the threshold is determined based on real time or near realtime data from the pressure measuring device 14. In yet anotheralternative, the threshold is established as a multiple of thebackground pressure or flow rate of the high-pressure fluid supply.

In block 104, a signal from the pressure measuring device 14 is analyzedfor signals that exceed the threshold to establish the occurrence of anevent. The signal from the pressure measuring device 14 corresponds tothe pressure, the flow rate, or both the pressure and flow rate of thehigh-pressure fluid supply measured by the pressure measuring device 14.An event may be identified as a signal from the pressure measuringdevice 14 that exceeds the threshold. In an embodiment, the event is asignal that significantly exceeds the threshold as determined bystatistical analysis. In an alternative embodiment, the event is asignal that exceeds the threshold by a predetermined value orpercentage.

In block 106, the location of the nozzle 28 is identified at theoccurrence of the event. In an embodiment, the location of the nozzlemay be identified by recording the time of the occurrence of the eventduring a stroke of the sootblower 16 and correlating that time with thelocation of the nozzle 28. Other methods of identifying the location ofthe nozzle 28 of the sootblower 16 at the occurrence of an event may beemployed, such as the use of rotational and displacement measurementsensors.

In block 108, the location of the nozzle at the occurrence of an eventis recorded as the location of a potential deposit.

The analytical process 100 set forth in FIG. 3 may be repeated for eachstroke of a sootblower 16 into and out of a boiler system. In anembodiment, the location of a potential deposit recorded in a firststroke is compared with the location of a potential deposit recorded ina second stroke. If the location of a potential deposit recorded in afirst stroke is near to or the same as the location of a potentialdeposited recorded in a second stroke, then the presence of a deposit atthe location may be considered to be confirmed. In some embodiments, thesootblower 16 does not follow the same helical path on the way into theboiler system as it does on the way out. In such embodiments, a depositrecorded in a first stroke might not be recorded for the second stroke.Additionally, the pressure in the high-pressure fluid supply thatresults from the expelled high-pressure fluid during insertion maydiffer from the pressure in the high-pressure fluid supply duringextraction. As such, deposits that may be detected in a first strokemight not be detected in a second stroke.

The frequency or high-pressure fluid output delivered by particularsootblowers 16 may be adjusted in accordance with their respectivepressure measurements. By reviewing the pressure differences indicativeof deposits 20 on the heat exchangers 22 that area associated withindividual sootblowers 16, or groups of sootblowers 16, the boileroperator may develop an understanding of locations in the boiler 12where the most deposit 20 buildup or fouling is occurring. Thisinformation may be used to establish the frequency of operation orhigh-pressure fluid output delivered to particular sootblowers 16 forreducing fouling and improving boiler 12 efficiency by using only anamount of high-pressure fluid 24 necessary to remove deposits 20. Theinformation may also be used to adjust boiler 12 conditions orconfigurations to reduce fouling at particular locations. For example,the information may be used to improve the design of the boiler 12 toreduce fouling or to identify locations within the boiler 12 foradditional or reduced fouling abatement mechanisms.

The deposit detection device 18 (FIG. 1) receives signals from thepressure measuring devices and may optionally control the operation ofthe cleaning implement, such as a sootblower lance tube 26, based on thedeposits 20 located on one or more of the heat exchanger surfaces 48.The deposit detection device 18 may also control the amount ofhigh-pressure fluid 24 supplied or the high-pressure fluid's 24 flowrate to the heat exchanger surfaces 48 during cleaning portions of theinsertion and extraction strokes and during cooling portions of theinsertion and extraction strokes when steam is used to keep thesootblower from overheating but not for cleaning purposes. The depositdetection device 18 generally includes a processing unit and a memorydevice. The deposit detection device 18 may be implemented as a computer(not shown) programmed to carry out the tasks described. The depositdetection device 18 may also be implemented using hardware, software, orcombinations thereof. The memory may be encoded with computer readableinstructions that cause the processing unit to perform the data analysisdescribed herein.

The deposit detection device 18 may communicate with the integrateddevice 30, which provides control signals to the cleaning implement,such as a sootblower lance tube 26, to start and stop the cleaningimplement strokes. Accordingly, the integrated device 30 may control thefrequency of use of each of the cleaning implements. The integrateddevice 30 may also provide signals to a data acquisition system (notshown) indicating when individual cleaning implements, or groups ofcleaning implements, are at particular locations of their strokes. Forexample, the integrated device 30 may provide a signal to the dataacquisition system when a particular cleaning implement begins a strokeand when the particular cleaning implement ends its stroke. Furthermore,the integrated device 30 may indicate the insertion and extractionportions of the stroke. The data acquisition system may utilize thesignals indicative of the beginning and the end of a particular cleaningimplement stroke to identify pressure measurements from the pressuremeasuring device 14 occurring at or near the beginning and the end ofthe cleaning implement stroke. The deposit detection device 18 may thenutilize statistical techniques to manipulate the pressure or flow ratedata associated with individual cleaning implement or groups of cleaningimplements. The pressure characteristics such as the pressure change orflow rate of the high-pressure fluid supply can be used to select asuitable frequency for operation of the cleaning implements or ahigh-pressure fluid 24 output of the cleaning implements.

The data acquisition system generally includes a processing unit and amemory device. The data acquisition system may be implemented as acomputer (not shown) programmed to carry out the tasks described. Thedata acquisition system may also be implemented using hardware,software, or combinations thereof. The memory may be encoded withcomputer readable instructions that cause the processing unit to performthe data analysis described herein. The data acquisition system may be astandalone device or part of the deposit detection devices 18 or theintegrated device 30. In some embodiments, the deposit detection device18, the integrated device 30, and the data acquisition system arecombined in a single unit. It is to be understood that the location andconfiguration of the deposit detection device 18 and the integrateddevice 30 are flexible in accordance with general computing technology.

By selecting frequencies or high-pressure fluid 24 usage for individualcleaning implements or groups of cleaning implements based on theirmeasured performance, the overall amount of the high-pressure fluid 24utilized by the cleaning implements may be reduced and the effectivenessof the cleaning implements improved. This technique can improve theoverall efficiency of the boiler 12, which may allow the boiler system10 to consume less fuel for the same high-pressure fluid 24 output or tooperate longer without shutdown (scheduled or unscheduled) due toplugging.

While the present invention has been illustrated by the description ofspecific embodiments thereof, and while the embodiments have beendescribed in considerable detail, it is not intended to restrict or inany way limit the scope of the appended claims to such detail. Thevarious features discussed herein may be used alone or in anycombination. Additional advantages and modifications will readily appearto those skilled in the art. The invention in its broader aspects istherefore not limited to the specific details, representative apparatusand methods and illustrative examples shown and described. Accordingly,departures may be made from such details without departing from thescope or spirit of the general inventive concept.

1. A boiler system comprising: a boiler having at least one heatexchanger, the at least one heat exchanger having a surface on which adeposit may form; at least one cleaning implement having a tube forcarrying a high-pressure fluid into the boiler, the tube being fluidlycoupled to a high-pressure fluid supply and configured to discharge thehigh-pressure fluid such that the high-pressure fluid impacts at leastone of the heat exchanger surface and/or internal boiler wall surface;and at least one pressure measuring device coupled to the high-pressurefluid supply, the pressure measuring device being configured to measurethe changes in at least one of the pressure or flow rate in thehigh-pressure fluid supply resulting from the impact of thehigh-pressure fluid with a deposit, wherein the measured pressure of thehigh-pressure fluid indicates presence or absence of the deposit on theat least one of heat exchanger surface or internal boiler wall surface.2. The boiler system of claim 1, wherein the measured pressure of thehigh-pressure fluid supply indicates at least one of a location of thedeposit or an amount of the deposit on the at least one of heatexchanger surface or internal boiler wall surface.
 3. The boiler systemof claim 1, wherein the at least one pressure measuring device islocated in at least one of a high-pressure fluid line carrying thehigh-pressure fluid supply to at least one cleaning implement or ahigh-pressure fluid line carrying the high-pressure fluid supply to morethan one cleaning implement.
 4. (canceled)
 5. The boiler system of claim1, wherein the at least one pressure measuring device is in fluidcommunication with the high-pressure fluid in the cleaning implement. 6.The boiler system of claim 1, wherein the at least one pressuremeasuring device is selected from the group consisting of a pressuretransducer, a flow rate measurement device, and combinations thereof. 7.The boiler system of claim 1 wherein the cleaning implement is selectedfrom the group consisting of a sootblower and a water cannon.
 8. Theboiler system of claim 1 further comprising a vibration measuringdevice.
 9. A method of detecting a deposit on a surface disposed withina boiler system, the method comprising: moving a cleaning implementcoupled to a high-pressure fluid supply relative to the surface;impacting the surface with a high-pressure fluid discharged from thecleaning implement; measuring at least one of a pressure or flow rate inthe high-pressure caused by the impact of the high-pressure fluid at alocation on the at least one of the pressure or flow rate; and analyzingthe measured pressure to detect the presence of the deposit at thelocation.
 10. The method of claim 9, further comprising: controlling aflow characteristic of the high-pressure fluid discharged from thecleaning implement at the location of the surface in response to themeasured at least one of the pressure or flow rate.
 11. The method ofclaim 10, wherein the flow characteristic is selected from the groupconsisting of an amount of high-pressure fluid discharged from thecleaning implement, a flow rate of the high-pressure fluid, andcombinations thereof.
 12. The method of claim 9 one of claims 9 to 11,wherein the step of measuring a pressure further comprises: dynamicallymeasuring pressures in the high-pressure fluid supply caused by theimpact of the high-pressure fluid with the surface at each of aplurality of locations, wherein the step of analyzing the measuredpressure further comprises analyzing the measured pressure in thehigh-pressure fluid supply caused by the impact of the high-pressurefluid with the plurality of locations on the surface, the method furthercomprising: generating a map of the locations of any detected depositson the surface.
 13. The method of claim 12, further comprising:controlling a flow characteristic of the high-pressure fluid dischargedfrom the cleaning implement while moving the cleaning implement relativeto the at least one heat exchanger surface based on the map of detecteddeposits.
 14. The method of claim 13, wherein the flow characteristic isgreater for a location of the surface having a greater amount of depositthan for a location of the surface having a lesser amount of deposit.15. The method of claim 9, wherein the pressure is measured with atleast one pressure transducer coupled to at least one of thehigh-pressure fluid supply, the cleaning implement, a high pressurefluid line supplying high-pressure to at least one cleaning implement,or combinations thereof.
 16. (canceled)
 17. (canceled)
 18. The method ofclaim 9, wherein the impacting of the surface with high-pressure fluidremoves at least a portion of the deposit at the location on thesurface, the method further comprising: measuring a first pressure at afirst time point caused by the impact of the high-pressure fluid at thelocation of the surface; measuring a second pressure at a second timepoint caused by the impact of the high-pressure fluid at the location ofthe surface; and comparing the first pressure to the second pressure todetermine changes in the amount of the deposit on the surface at thelocation.
 19. The method of claim 9, wherein the greater the measuredpressure in the high-pressure fluid supply when impacting the surface atthe location on the surface, the greater an amount of the deposit at thelocation on the surface.
 20. The method of claim 9 wherein the surfaceis selected from the group consisting of a heat exchanger surface, aninternal boiler wall surface, and combinations thereof.
 21. The methodof claim 9 wherein the cleaning implement is selected from the groupconsisting of a sootblower and a water cannon.
 22. A method of analyzinga surface of a boiler system, the process comprising: passing a cleaningimplement coupled to a high-pressure fluid supply through a boiler in afirst pass and contacting a surface in the boiler with a high-pressureexpelled from the cleaning implement; receiving a first signalindicative of a pressure in a high-pressure fluid supply in the boilersystem; and in response to the signal exceeding a threshold, determiningthe existence of a deposit on the surface of the boiler.
 23. The methodof claim 22, further comprising: identifying the position of thecleaning implement when the signal exceeds the threshold; anddetermining a position of the deposit in the boiler based on theposition of the cleaning implement when the signal exceeds thethreshold. 24-30. (canceled)